    Patent document 1: JP-B-59-39481    Patent document 2: JP-B-7-91569
Conventionally, as multilayered sintered sliding members, there are known a so-called wound bush bearing in which a porous sintered alloy layer is integrally bonded to an obverse surface of a thin steel plate and a laminate thereof is convoluted with the sintered alloy layer placed on the inner side, as well as a cylindrical sliding member in which a porous sintered alloy layer is integrally bonded to an inner surface of a steel pipe by means of an adhesive. With the former wound bush bearing, however, a large compressive stress is applied to the sintered alloy layer at the time of bending into the cylindrical shape, so that there is a possibility of causing a decline or nonuniformity in the bonding strength between the thin steel plate and the sintered alloy layer. In addition, with the method based on bending, the thickness of the sintered alloy layer cannot be made large, so that a problem is involved in that the range of use as the sliding member is naturally limited. In addition, with the latter cylindrical sliding member, there is a problem in that firm bonding strength is difficult to obtain between the inner surface of the steel pipe and the porous sintered alloy layer.
In view of the above-described circumstances, the present applicant proposed a multilayered sintered sliding member wherein a porous sintered alloy layer having copper (Cu) as a principal component and additionally consisting of fixed amounts of tin (Sn), nickel (Ni), phosphorus (P), and graphite (C) is integrally bonded to an inner surface of a backing plate constituted by a steel pipe and a multilayered sintered sliding member wherein the porous sintered alloy layer further having a fixed amount of iron (Fe) added thereto is integrally bonded thereto (Patent Document 1), as well as a multilayered sintered sliding member wherein a porous sintered alloy layer similar to the above-described one is integrally bonded to an obverse surface of a backing plate constituted by a steel plate (Patent Document 2).